- extend docker-compose.yml with a custom field to define image hierarchy
- added docker and docker-compose commands to archery
- validate docker-compose configuration's custom fields as well exercising docker-compose's builtin validation
- covered the added features with unittests
- archery command to execute the pull/build/run docker-compose sequences
- archery support for python 3.5, also test it on github actions
- updated all of the github workflows to use the new archery tooling
- updated all of the crossbow tasks to use archery as well
- removed the old Makefile.docker
- fixed archery's package and module definitions, because a non-editable installation caused import errors
- added documentation

Closes #7021 from kszucs/archery-docker

Authored-by: Krisztián Szűcs <szucs.krisztian@gmail.com>
Signed-off-by: Krisztián Szűcs <szucs.krisztian@gmail.com>